It runs ridiculously slowly for me. I find playing it on my 8 year old laptop it works at full speed, whereas my 3 month old gaming rig it crawls along. Have found no help online, no amount of restarting or killing processes has helped.

It slowed down for me earlier. I was playing with the keyboard, but found the receiver for my Xbox controller. I turned the game off and unplugged the receiver, started the game later because I was board, but didn't turn on the controller. It ran slow, but went back to normal when I plugged the receiver back in.

tl;dr: Ran slow without controller, normal with it. But it ran normal without it in the beginning, so it's probably just a coincidence.